Ion mobility spectrometers realize differentiation of ions according to different drift speeds of different ions in a uniform weak electric field. Ion mobility spectrometers are widely used in many fields, such as detection of drugs and explosives, due to their high differentiation speed, high sensitivity, absence of a vacuum environment and ease of miniaturization.
A typical ion mobility spectrometer usually consists of a sample injection part, an ionization part, an ion gate, a migration zone, a collection zone, a readout circuit, a data acquisition and processing part, a control part etc. The ionization part has a primary function of converting sample molecules into ions for migration and separation, and an ionization effect of the ionization part has a very direct impact on performance of the ion mobility spectrometer.
In order to achieve better ionization performance, an ion mobility spectrometer which performs ionization using corona discharge has been used. Corona discharge refers to a phenomenon in which ionization of gas molecules is caused by a local strong electric field in a spatial non-uniform electric field. Ions generated directly by corona discharge are generally referred to as reactant ions. When sample molecules with a high proton or electron affinity pass through the ionization zone, they may be ionized by trapping charges of reactant ions. A common corona discharge structure is simple and has a low cost, and may produce a high charge concentration, thereby greatly improving sensitivity and a dynamic range of the ion mobility spectrometer.
However, the high charge concentration generated by corona discharge further requires the ion mobility spectrometer to collect and process the charges more properly; otherwise it may seriously affect the stability of the device. How to achieve a more stable corona discharge based ion mobility spectrometer is one of the most urgent problems in the related art.